How does an evaporative cooling system work?

Pad cooling systems utilize the cooling effect created by the evaporation of water in warm outside air. Incoming air is drawn through a plastic pad that is wetted and mounted in front of the air intake. Ducts above the cooling pad distribute the water flow evenly so that the entire surface area of the pad is wetted. As the water passes through the cooling pad, it partially evaporates. During this evaporation, heat is extracted from the air, thereby lowering the temperature. At the bottom of the cooling pad, the water is collected in a chute and circulated for reuse.